This invention relates to a composition and method for removing paint films from surfaces and more particularly it relates to a novel additive for increasing the effectiveness of alkaline stripping compositions.
In the manufacture of various commercial articles, it is often the practice to provide such articles with a protective and/or decorative paint film on the surface. The term "paint" as used herein includes paints, varnishes, lacquers and the like, which are formulated from numerous and diverse components, including acrylic resins, epoxy resins, vinyl resins, alkyd resins, and the like.
In the course of manufacturing these commercial articles, it sometimes happens that some of the articles fail to meet the manufacturing specification because of some defect in the protective and/or decorative coatings which are applied. When this happens, it is desirable to remove the defective coating from the article so that it may be recoated rather than discarded or sold as a "second" with resulting financial loss. In recent years, however, great improvements have been made in both the durability and adhesion of paints and similar protective coatings so that their removal from a surface after they have been applied, cured and/or dried, has become increasingly difficult. These difficulties have been encountered particularly when using chemical means to effect the removal of the coatings, such chemical removal methods generally being preferred because they tend to limit costly hand operations and are more readily adapted to a continuous process.
Not only is it desirable to remove the paint on articles from which the coating is defective, but, additionally, where the articles being coated are transported on a conveyor line, the hooks which support the article also become coated with the paint or similar coating during the process. Since these hooks or hangers are repeatedly introduced into the painting zone of the process, the paint continues to build up on them adding weight to the conveyor line and often filling in the hook, if it is not periodically stripped off or removed. Accordingly, it is desirable to remove such protective coatings from these hooks or hangers as well as from defective articles, quickly and completely, and preferably by using chemical means.
In the past, considerable use has been made of alkaline stripping compositions in which the article from which the protective coating is to be removed is immersed for a period of time sufficient to effect a substantial loosening of the coating. With the advent of improved paint systems, such as the acrylic paints and lacquers, difficulties have often been encountered with such alkaline stripping compositions. Frequently, it has been found that the articles must be immersed in a boiling alkaline stripping composition for several hours in order to obtain the desired loosening of the protective coating. In some instances, even longer contact times have not resulted in an appreciable loosening of the coating.
U.S. Pat. No. 3,615,827 suggests an alkaline stripping composition containing a phenol derivative. Since phenol compounds have come under the increasing scrutiny of environmental interests and administrations of the Occupational Safety and Health Act, it would be desirable to eliminate their use. U.S. Pat. Nos. 3,663,447; 3,663,476; and 3,671,465 disclose stripping compositions containing amine compounds but only as additives for glycol or phenol systems.